BioStar 2 API supports both http and https protocols. When you use https protocol, you should follow below steps to apply your own certification. 

1. Stop the API Server.
2. Copy the certificate file you want to replace to \BioStar 2 API Server (x64)\certs and replace the existing server.crt, server.key files.
3. Copy the attached file (update_certs.js) to \BioStar 2 API Server (x64)\dist.
4. Open a command window and go to BioStar 2 API server (x64) folder and run nodejs\node.exe dist\update_certs.js